Don't optimize special dynamic calls to non-dynamic

As it drops the warning. This is more problematic with constant
propagation, as tests would fail.

Extract a zend_optimizer_classify_function() function, as its now
needed by zend_cfg and update_opN.

Author: nikic

Zend/tests/dynamic_call_008.phpt

@@ -0,0 +1,13 @@
+--TEST--
+Don't optimize dynamic call to non-dynamic one if it drops the warning
+--FILE--
+<?php
+
+function test() {
+    ((string) 'extract')(['a' => 42]);
+}
+test();
+
+?>
+--EXPECTF--
+Warning: Cannot call extract() dynamically in %s on line %d

ext/opcache/Optimizer/zend_cfg.c

@@ -21,6 +21,8 @@
 #include "zend_cfg.h"
 #include "zend_func_info.h"
 #include "zend_worklist.h"
+#include "zend_optimizer.h"
+#include "zend_optimizer_internal.h"
 
 static void zend_mark_reachable(zend_op *opcodes, zend_basic_block *blocks, zend_basic_block *b) /* {{{ */
 {
@@ -319,27 +321,8 @@ int zend_build_cfg(zend_arena **arena, const zend_op_array *op_array, uint32_t b
 				}
 				if ((fn = zend_hash_find_ptr(EG(function_table), Z_STR_P(zv))) != NULL) {
 					if (fn->type == ZEND_INTERNAL_FUNCTION) {
-						if (zend_string_equals_literal(Z_STR_P(zv), "extract")) {
-							flags |= ZEND_FUNC_INDIRECT_VAR_ACCESS;
-						} else if (zend_string_equals_literal(Z_STR_P(zv), "compact")) {
-							flags |= ZEND_FUNC_INDIRECT_VAR_ACCESS;
-						} else if (zend_string_equals_literal(Z_STR_P(zv), "parse_str") &&
-						           opline->extended_value == 1) {
-							flags |= ZEND_FUNC_INDIRECT_VAR_ACCESS;
-						} else if (zend_string_equals_literal(Z_STR_P(zv), "mb_parse_str") &&
-						           opline->extended_value == 1) {
-							flags |= ZEND_FUNC_INDIRECT_VAR_ACCESS;
-						} else if (zend_string_equals_literal(Z_STR_P(zv), "get_defined_vars")) {
-							flags |= ZEND_FUNC_INDIRECT_VAR_ACCESS;
-						} else if (zend_string_equals_literal(Z_STR_P(zv), "assert")) {
-							flags |= ZEND_FUNC_INDIRECT_VAR_ACCESS;
-						} else if (zend_string_equals_literal(Z_STR_P(zv), "func_num_args")) {
-							flags |= ZEND_FUNC_VARARG;
-						} else if (zend_string_equals_literal(Z_STR_P(zv), "func_get_arg")) {
-							flags |= ZEND_FUNC_VARARG;
-						} else if (zend_string_equals_literal(Z_STR_P(zv), "func_get_args")) {
-							flags |= ZEND_FUNC_VARARG;
-						}
+						flags |= zend_optimizer_classify_function(
+							Z_STR_P(zv), opline->extended_value);
 					}
 				}
 				break;

ext/opcache/Optimizer/zend_optimizer.c

@@ -254,6 +254,13 @@ int zend_optimizer_update_op2_const(zend_op_array *op_array,
 					return 0;
 				}
 
+				if (zend_optimizer_classify_function(Z_STR_P(val), opline->extended_value)) {
+					/* Dynamic call to various special functions must stay dynamic,
+					 * otherwise would drop a warning */
+					zval_dtor(val);
+					return 0;
+				}
+
 				opline->opcode = ZEND_INIT_FCALL_BY_NAME;
 				drop_leading_backslash(val);
 				opline->op2.constant = zend_optimizer_add_literal(op_array, val);
@@ -584,6 +591,30 @@ zend_function *zend_optimizer_get_called_func(
 #undef GET_OP
 }
 
+uint32_t zend_optimizer_classify_function(zend_string *name, uint32_t num_args) {
+	if (zend_string_equals_literal(name, "extract")) {
+		return ZEND_FUNC_INDIRECT_VAR_ACCESS;
+	} else if (zend_string_equals_literal(name, "compact")) {
+		return ZEND_FUNC_INDIRECT_VAR_ACCESS;
+	} else if (zend_string_equals_literal(name, "parse_str") && num_args == 1) {
+		return ZEND_FUNC_INDIRECT_VAR_ACCESS;
+	} else if (zend_string_equals_literal(name, "mb_parse_str") && num_args == 1) {
+		return ZEND_FUNC_INDIRECT_VAR_ACCESS;
+	} else if (zend_string_equals_literal(name, "get_defined_vars")) {
+		return ZEND_FUNC_INDIRECT_VAR_ACCESS;
+	} else if (zend_string_equals_literal(name, "assert")) {
+		return ZEND_FUNC_INDIRECT_VAR_ACCESS;
+	} else if (zend_string_equals_literal(name, "func_num_args")) {
+		return ZEND_FUNC_VARARG;
+	} else if (zend_string_equals_literal(name, "func_get_arg")) {
+		return ZEND_FUNC_VARARG;
+	} else if (zend_string_equals_literal(name, "func_get_args")) {
+		return ZEND_FUNC_VARARG;
+	} else {
+		return 0;
+	}
+}
+
 static void zend_optimize(zend_op_array      *op_array,
                           zend_optimizer_ctx *ctx)
 {

ext/opcache/Optimizer/zend_optimizer_internal.h

@@ -108,5 +108,6 @@ void zend_optimizer_compact_literals(zend_op_array *op_array, zend_optimizer_ctx
 int zend_optimizer_is_disabled_func(const char *name, size_t len);
 zend_function *zend_optimizer_get_called_func(
 		zend_script *script, zend_op_array *op_array, zend_op *opline, zend_bool rt_constants);
+uint32_t zend_optimizer_classify_function(zend_string *name, uint32_t num_args);
 
 #endif